Pump and pressure-reservoir for brakes or the like.



C. J. SPENCER & J. W. DAWSON.

PUMP AND PREssuRE RESERVOIR FOR BRAKES OR THE LIKE.

APPLICATION FILED JUNE 16. 1915.

1,158.,UUT. Patented Oct. 26, 19 15.

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TED AEfl PATENT GHBIfi'IOPHER JOHN SPENCER AND JOHN WILLIAM DAWSQN, OF BRADFORD, ENGLAND.

PUMP AND PRESSURE-RESERVOIR FOR BRAKES OR THE Specification of Letters Eatent.

Patented (lot. 25, 1915..

Application filed. June 16. 1915. Serial No. 3 1,446.

To all whom it mag concern:

Be it known that we, Grrnrsrorirnn J OHN SPENCER and JOHN WILLIAM Dawson. subjects of the King of Great Britain and Ireland, and both residing at The Tramway Ofiices, Hall Ings, Bradford, Yorkshire, England, have invented new and useful improvements in or Connected with Pumps and Pressure-Reservoirs for Brakes or the like, of which the following is a specification.

This invention relates to improvements in the maintaining of a supply of compressed gas in pressure reservoirs or the like containing fluid, which fluid is withdrawn from the reservoir to accomplish its object, such as the actuation of brakes and then pumped back thereto after the manner as set out in our specification of British Letters Patent No. 874.0 of 1911 wherein a quantity of compressed. gas acted as an elastic medium or stored energy to eject or assist in ejecting the fluid from the reservoir in such'cases where the fluid is alternately forced into and ejected out of the reservoir and further to supply gas in quantities equal or more than equal to the quantity absorbed by the fluid with which it is in contact and under pressure.

While the apparatus is primarily intended for use with brakes for tramway or other vehicles after the manner set out in our before mentioned British patent, it may be used for other purposes for example, the maintenance of air in vessels used in connection with hydraulic pumps or for pumpgases along with fluids for thepurpose of adding an elastic medium to the otherwise incompressible fluid. in order to secure a continuous flow of such fluids although their initial. motion may be intermittent (or pulsating) Vi e have found by experiment that when air or other compressible gas is in contact and under pressure with oil or other viscous fluidsthat a quantity of gas is absorbed by the fluid, and that the quantity of gas absorbed is in some relation to the amount of pressure to which they are subjected and further such gases are released when the pressure is reduced. In the case of air and water it is known that the quantity of air absorbed is almost in proportion to the pressures to which the water and air may be submitted and as before mentioned our experiments have shown us that other fluids such as oil also absorb air or gases under like conditions,

In apparatus such as "described in the specification of British Patent N0. 8740 of 1911 wherein a reservoir is used containing a compressible gas and a fluid such as oil, under pressure, and where the fluid is alternately withdrawn from and returned to (or replaced by other fluid) in the reservoir, such fluid we have found absorbs a quantity of the gas or air and when exhausted from the reservoir carries the absorbed with it. This gas is released when the pressure on the fluid is sufliciently reduced. It is therefore necessary in this and like cases where it is required to maintain the quantity of gas in the reservoir approximately constant, that sufficient gas should be introduced to compensate for the amount eX- hausted with the fluid.

Therefore, our objects are to provide, first, a suitable vessel or reservoir to contain liquid and a compressible gas, which liquid will be from time to time withdrawn to accomplish its desired function and then returned to the reservoir. Second, a pump adapted to pump the used liquid from a suit able sump back to the reservoir, said pump being so constructed as not to pump air alone, but to pump air or gas and liquid in such wise that the pressure in the reservoir will thereby be maintained, and in this maintenance of pressure we utilize the property of absorption of gases by suitable fluids according to the pressures to which they may be subjected and are thereby enabled to control the amount of gas in the reservoir. The greater the gas pressure in the reservoir the more gas will. be absorbed by the liquid and vice versa and therefore at high gas pressure will escape with the liquid as it is used than will be the case with a low pressure. Third, we may provide means adapted to augment the air-or gas supply over and above that provided by the pump.

To accomplish our objects we use a suitable reservoir and a pump provided with an internal space and so proportioned that when no liquid is present in the pump, the operation and construction of thepump is such that the pressure of a. full charge of air or gas compressed by the pump will not be equal. to or exceed the working pressure in the storage reservoir and therefore the air cannot be passed forward to the reservoir. Further this inner space 1s opened to atmosphere at the end of each inner stroke of the plunger, therefore when ,no liquid is available charges of air drawn tical and inverted.

in by the outward stroke are exhausted to atmosphere at'the end of the inner strokes. This space plus means for opening same to atmosphere is an essential part of our invcntion. When liquid is provided, a charge of air plus liquid will be delivered to the liquid is drawn into the pump "through one and the same .port but at different times andthe gas and liquid are passed forward at one particular stroke on the operation of the pump through one delivery aperture to the reservoir.

In describing our invention in detail, reference is made to the accompanying sheets ofdrawings, similar letters indicating similar p'arts in which Figures 1 and 2 show a pump and reservoir constructed according to our invention. Fig. 3 shows a pump of slightly modified construction. The normal position of the pump in Fig. 1 is horizontal and the normal position of the pump in Fig. 3 is ver- To carry out our invention the working storage vessel or reservoir V (Fig. 2) is provided with'a suitable aperture or apertures such as V through which the required quantities of gas may be introduced, such aperture being preferably closed, by means of any suitable valve of the automatic or controlled type suitably placed in the pipe or like V but not shown in the drawings,

the required quantity of gas being passed into the reservoir together with the liquid through one and the same aperture by means of a suitably designed pumping apparatus P (Figs; 1 and'8) so arranged that gas will be passed along with the liquid, a portion of the gas being absorbed when the'pressure produced by the pump plunger is applied and portion (the remainder) added to that in thereservoir. In case more gas is required than that supplied by the combined gas and fluid pump the as supply may be augmented from a separate source through a separate aperture V through which the required quantities of gas may be introduced. I

1n the case of brake mechanism according to our before mentioned specification of British Letters Patent a pump P with suitable valve arrangements is shown and described in connection with a reservoir, such pump being designed not to'pass any air or other gas into the reservoir. In accordance with ourpresent invention and in order to enable this or a like pump P to pass the desired quantity of gas or air into the reservoir V ranged as shown by full lines in Fig. 1

(which said reservoir will contain a suitable liquid in addition to the gas) the pump to carry out our objects may vary in construction so long as it contains the essential features before referred to.

To render clear the action and purpose of the pump P we will take it that the pump is a new one and is merely charged with air, and no liquid is available; as the pump is operated the action of the plunger I when nearing the inner end of its stroke is to compress the air. The clearance space of the pump, namely that space not occupied by the plunger at theinnermost end of its stroke coupled with the space under the outlet valve is so proportioned that the pressure exerted by the plunger is not equal to or will not exceed the lowest working pressure in the reservoir V to which the pump is connected, and therefore the valve P will not open. At the innermost end of the stroke-the passage A in the plunger will open to atmospher and allow the air remaining in the clearance space to be at atmospheric pressure, therefore when no liquidis available no air will be pumped. When, however, liquid is available such as from thesi mp to which it has run after passing, from the reservoir to accomplish its purpose, the first suction stroke of the plunger-will draw in liquid to an amount approximately equal to the displacement of the plunger, and the available space in the pump now contains liquid and airon the inward stroke the air will be compressed until the pressure is suflicient to open the valve P and thereby pass air and liquid to the reservoir. At the end of the inward stroke the passage A is open to atmosphere and a small quantity of the liquid is ejected, this ejected liquid may serve to lubricate the variousoperating levers or rods. The air iaving been passed to the reservoir, only liquid willthen be pumped until the supply in the sump is exhausted. There will, now that the pump has drawn in liquid always remain in the pump barrel a quantity of liquid suflieient to reach. to the level of the atmosphere communicating passage A and in the drawings I have designated this liquid by L and called the space above and that under the outlet valve S. As will be understood this space S may be designed and constructed to meet varying requirements.- If,for example, the passage A is ar- 3 the space S willbe comparatively small in bulk. Should, however, the passage A. be made nearer tothe'inlet valve as shown by dotted lines the space S will be increased and so make available to be passed to the reservoir a larger quantity of air. The space shown under the inlet valve P may be enlarged or contracted by cutting away or filling-in;

In Fig. 2 the space S may be increased from that shown by dotted lines by 'constructing same nearer to the plunger head as shown by full lines.

Thus it will be seen that the capacity of the space S is dependent on the passage A and its position and the passage A is only open to atmosphere when the plunger is nearly in its innermost position.

In operation as before described the pump will first pass air and fluid to the reservoir, afterward fluid only will be passed until the amount in the sump has been exhausted. When a further supply of fluid in the sump has been provided, the operation before de scribed will be repeated.

In the case of pumps which are working more or less continuously and in which it is desired to include a quantity of air with the fluid, any suitable auxiliary valves placed at or about the position indicated by I in Fig. 1 may be arranged which will admit a quantity of air or gas at or toward the end of the stroke in such a manner that it will be pumped forward with the charge of fluid.

Accordin to our invention we utilize the property which suitable fluids have to absorb gases under the pressures to which they are submitted, in order to prevent an undue accumulation or exhaustion of the gases in or from the reservoir.

If more gas is passed into the reservoir than is necessary to take the place of the amount absorbed and withdrawn by the fluid as same is used to accomplish its purpose, the pressure in the reservoir will be increased and more gas will be absorbed by the fluid than is the case at lower pressure, and if too little gas is supplied the pressure will be reduced and less gas will be absorbed and carried from the reservoir by the fluid when same is used for its purpose.

o provide means for augmenting the air 01' gas supply in the reservoir V to maintain an approximately constant gas pressure.

An arrangement for augmenting the gas or air supply for the working reservoir V is shown in Fig. 2 wherein the fluid and air or gas from the pump is admitted to the reservoir V through the aperture V, and inlet V provided with a suitable valve V is connected either to an auxiliary gas or air storage reservoir V in which. a constant pressure is maintained by means of a suitable gas or air compressor arranged that when the pressure in the reservoir V is reduced to a predetermined amount below that in the reservoir V 3 the-valve V will open and allow gas to pass from reservoir V to reservoir V and so augment the gas supply.

What we claim is 1. A device of the class described including a pump provided with a casing having a clearance space provided with an inlet and an outlet and having a lateral port, a plunger operating in the casing and having a passage affording communication between the port and space when in innermost position, the clearance space of the pump coupled with the space under the outlet being so proportioned that the pressure exerted by the plunger will not exceed the lowest work ing pressure in the reservoir to which the pump is connected and a reservoir connected with the outlet as and for the purposes described.

2. In combination with a pressure reservoir from and to which fluid is alternately withdrawn and returned, a pump adapted in returning the fiuid to pass therewith an amount of air requisite to maintain the desired pressure in the reservoir, said pump having a valved inlet and a valved outlet, said inlet having connection with a suitable liquid chamber such as a sump, the space not occupied by the plunger of the pump when at the innermost end of its stroke being such that the pressure exerted by the plunger will not exceed the lowest working pressure of the reservoir whereby when there is no liquid in said sump, said outlet valve will be prevented from opening but whereby when liquid is available for supply through the inlet on the suction stroke of the pump, the same will be drawn into said space and forced through said valved outlet for supplying the same with the air compressed and absorbed thereby to the reservoir for use as desired, said plunger having a longitudinal passage therethrough leading from its head end and extending laterally intermediately of its end and the casing of the pump having a passa e opening to the atmosphere and to aline with the lateral portion of said passage in the plunger whereby to place said space in communication with the atmosphere to permit the escape of air therethrough when air only is available, but to permit a portion of said liquid to escape therethrough for lubricating purposes when liquid is available and is forced into the reservoir as above specified.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

CHRISTOPHER JOHN SPENCER.

JOHN WILLIAM DAWSON.

IVitnesses:

CLIVE WAUGH, ToM PERCY SYKEs.

Uopies of this patent may be obtained for five cents each, by addressing the Gomxnissioner of Patents,

' Washington, D. C. 

